N-(1,3-Dimethylbutyl)-N

OECD SIDS
N-(1,3-DIMETHYLBUTYL)-N´-PHENYL-1,4-PHENYLENEDIAMINE
contrast for the oily preparation a PCII of 3.3 was reported which was evaluated as a medium
irritating effect (Herve-Bazin et al., 1977).
Conclusion: In view of possible vehicle effects on the observed irritant action and further
limitations of the study of Herve-Bazin et al. (1977) the assessment of skin irritation is based on the
first two studies (Randall and Bannister, 1990; Younger, 1962) that studied the irritant effect of
pure 6PPD. These studies gave evidence of a very low skin irritating potential of 6PPD.
Eye Irritation
There are no studies according to the current OECD guideline but there are study reports which give
sufficient information to evaluate this endpoint:
Undiluted 6PPD (0.1 ml) was applied to the eyes of 3 rabbits for 24 hours followed by a 5 day post
exposure period. After 1 hour slight edema and erythema, copious discharge and slight dullness of
the corneal area were observed with an average score of 20.6/110 according to the method of
Draize. Iris and cornea cleared somewhat in 24 hours and within 72 hours iris clarity was normal.
Very slight redness and edema disappeared by the 5 th day (Younger, 1962). Under similar test
conditions scoring of 6 rabbits in accordance with the Federal Hazardous Substance Act, 21 CFR,
paragraph 191.12 resulted in an average score of 1.2/110 (Randall and Bannister, 1990). Both
studies classified 6PPD as slightly irritating to the eye.
Conclusion: 6PPD was slightly irritating to the eye.
3.1.4 Sensitisation
The skin sensitizing potential of 6PPD was studied with the guinea pig maximization test. For
induction treatment groups of 20 female guinea pigs were intradermally injected with 0.5 % 6PPD
in olive oil with complete FCA followed one week later by cutaneous application of 1 % 6PPD in
petrolatum. According to the grading system of Magnusson and Kligman 50 and 90 %, respectively,
of the guinea pigs challenged by epicutaneous application of 0.05 and 0.5 % 6PPD in petrolatum
reacted positive. The sensitizing potential was classified as medium for the 0.05 % and very high
for the 0.5 % challenge concentration. 30 % of animals sensitized to 6PPD showed crosssensitization
to 0.05 % N-phenyl-N'-cyclohexyl-p-phenylenediamine (CPPD) in vaseline. Animals
sensitized to p-phenylenediamine (PPD) or to N-isopropyl-N‘-phenyl-p-phenylenediamine (IPPD)
showed also cross-sensitization to 6PPD (Herve-Bazin et al., 1977).
There are a number of human data available in section 3.1.9 Experience with Human Exposure.
Conclusion
6PPD was found to induce dermal sensitization in guinea pigs.
3.1.5 Repeated Dose Toxicity
The repeated dose toxicity of 6PPD in rats was investigated in two subacute gavage studies: A 28-
day repeat dose study according to the Japanese Guidelines for Toxicity Testing of Chemicals and a
preliminary reproduction toxicity screening test according to the OECD TG 421. Feeding for
periods of 13 weeks and 2 years (no guideline studies) gives information about subchronic and
chronic effects of 6PPD exposure in rats.
In the first guideline study groups of 5 male and female rats were exposed by gavage to 6PPD in
dosages of 0, 4, 20, 100 mg/kg bw/day (vehicle corn oil) for 28 days. The control and 100 mg/kg
group included additional 5 male and 5 female rats that were observed for further 14 days after
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